Stylus feed mechanism for phonographs



June 18, 1935. a R. F. MALLINA 2,005,583

STYLUS 'FEED' MECHANIS FOB PHONOGRAPHS Filed Aug. 28, 1951 A 7' TORNEV Patented 4June I8-, 1935 UNITED I^sx'm'rrzs STYLUS FED MECHANISM FOR PHONOGRAPHS Rudolph F. Mallina, New York,` N. Y., assigner to Bell Telephone Laboratories, Incorporated, New York. N. Y., a corporation of New York applicati@ August 28, 1931, serial 100.559.844 s Claims.. v(o1. 274-13) y v y with rough handling and varied air conditions.

Thisv invention relates to sound recording machines and particularly to the stylus feed mechanism thereof.

It is well knowni the art thatia recording stylus can be fedregularly across a record blank by connecting it to--a second stylus which is made to follow a groove-of the desired pitch cut into a disc of hard material. Such a disc may-be located on a separate mandrel or it may be placed underneath the turntable and concentric with it as is shown for example in United States Patent No.

1,008,605 to T. H. Macdonald, November 14, 1911.

Heretofore, however, it has been impractical to use this type of stylus feed for very fine pitch recording without employing reduction gearing for the feed disc which immediately increases the complexity of the `device and decreases the accuracy of 'the groove in the record blank. f

It is the object of this invention to provide a stylus feed mechanism whichis extremely simple and rugged, and-which may be used for either the ne pitch or coarse pitch type of recording with equal facility.

The means whereby this object is attained compitch cut thereon and a brush engaging the groove and secured to the recorder' arm to drive the latter across the turntable at a rate determined by the pitch of the groove on the disc.

Referring to. the accompanying drawing which illustrates 'one form of the invention:

Fig. 1 is a side elevation of a turntable and re corder;

Fig. 2 is the corresponding plan fview; and Fig. 3 is an enlarged view of the brush and turntable hub. l

In Fig. 1, IIJ is a recorder arm pivoted for vertical motion at II and for horizontal motion at I2 through the supporting member I3. The recorder I 4 may be of any well known make for either the lateral or hill-and-dale type of re` cording. A turntable I5 supports a record blank I6 and is driven from' a suitable source of power,

not shown, through a cone friction drive ar-4 is secured to th driveA shaft IBNtheA-frictional force between the two being relied upon to trans-A mit the required driving power to the turntable.

Thel friction drive makesl possible rapid removal and replacement of turntableswhenevendeslred.

Aclamping nut 20 holds the record blank in place.-

Underneath the turntable and concentric with it is a. grooved disc 2I ofmetal or otherv wear;

resistive material ca.p1 a `.b1e of `holding its `Shape prises a disc having a spiral groove of the desired` The groove is simply a spiral of the desired length, cut, stamped, or pressed into the surfaceof the disc and extending over an area equiva ',lerli to'or slightly larger than the one to be recorded en. Cooperating with the groove is a follower .22 at-v tached to an arm 23 which is pivotally secured to the recorder arm support I3 at 24.' A spring25- holds the follower 22 upward" against the grooved disc 2| while an adjustable extension 26 limits the vertical movement of the arm 23.

The follower 22 is preferably formed of a number of bristles of various lengths inclined away from the direction of rotation, and arranged according to length so that the shortest enter the grooves first. From the standpoint of transmission of power, it would be desirable to have all would have a tendency to, chatter and therefore would be somewhat irregular in its action. It has been found that by making the forward bristles short and stiff to carry the load and the succeeding bristles longer with a slight initial ilexure, the longer bristles will contact the groove under conditions which tend to throw the short stiff bristles out of contact and hence this arrangement' makes the action of the follower more regular.

The diameter of the bristles shouldl not exceed the width of the narrowest groove for which the machine is .designed but should be large erough to give the bristles maximum stiffness. The

shortest bristles may be only 116" long and the longest with the intermediate bristles taperof the bristles short and stiff, but such a Ifollower f ing of! evenly to give the follower a flat surface.

For the ordinary recorder a surface area of 1A of a square inch for the follower 22 is ample.

To operate thefrecorde'r a turntable with a disc i having a groove of' the desired pitchis selected and placed overthe cone IB ofthe drive shaft. A record is clamp d in placeand the turntable rotated. The rdingispreferably done from eedgegvof 'the record and accordingly the? 'recorder isswung` to the inside of the-record and the brushraised'until it engages the innermost groove` in the dlscfat which point disc. Just as soon as the brush is in contact with the discv the recorder can belowered onto theI blank` and thelsoundfcontrolled electrical cur- .lieptsffallowe'dstoactuate the recorder. If it is desired tomake severalshort records on one disc,

thlsgcanjbe-done simply by pushing the recorder .the brush will instantly begin to moveacross the j over slicrtjeistance withoutiiftmg 11: and the l recording'begun from that point immediately.

l When the record is finished the recorder is lifted l 2 i and carried overbeyond the-edge of the record in the usual manner. l a

.The many advantages of a feed mechanism of l this type are apparent. The total amount of vnorduced to an almost'negligible amount. The resilience of the bristles causes the follower to act as a filter for'vibrations arising out of irregularities in the grooves with -the result that the grooves cut in the record are often more perfect than those in the feed disc itself. The follower,

in addition, can be subiecte to rough usage without material damage to itself or to the feed disc. For example, it can be pushed laterally across the disc without being raised from it, aprocedure 20,

which wouldbe exceedingly harmful to a singlestylus feedl mechanism. It can be started anywhere on the disc without overlapping speech.

grooves or scratching the feed disc.

yAlthoughthis inventionjhas been described withreference to a disc andbrush as the essential components of the feed mechanism, I wish it understood that the -mechanism vcan be modifled considerably without departing from the 'spirit of the invention. 'I'he follower, for example, need not be limited to a brush Lbut can take the form of a block of fibrous orwire-like material which is capable of entering the grooves of turntable, a record blank, a recording stylus and means for driving the stylus across the record blank comprising a rotatable disc concentric with the turntable and having formed in its surface aspiral groove, a follower contacting a plurality of substantially adjacent sections of the groove, and

means for securing the follower to the stylus.

2. In a phonographic recording machine, a recording. stylus, and means for driving the stylus laterally comprising a member having formed thereon a groove, a follower for the groove comprised of a. plurality of bristles, and means for securing the follower to the stylus.

3.A In a phonographic recording machine a record blank, a turntable, a recording stylus cooperating with the record blank, and means for driving the stylus across the record blank, said means comprising ra rotatable disc beneath the turntable and having formedin a surface thereof a spiral groove, a resilient' follower for the groove contacting substantial adjacent sections oi' the groove, and meansy for securing the follower to the stylus.

RUDOLPH F. MALLINA. 

